A sealed single-dose package normally comprises a sealed sachet defining a sealed inner pocket containing a dose of a liquid product (e.g. sauce, such as ketchup, or liquid detergent) or a cream (e.g. sauce, such as mayonnaise, or skin cream). The sachet is torn open and, for this reason, has a small incision to tear it open easily.
It is extremely difficult, however, to achieve tear-open sachets that are both easy to open (i.e. with little effort) and yet strong enough to prevent them from being torn open accidentally (thus resulting in severe soiling, given the type of products contained in the sachets). The problem is further compounded in the case of sachets of detergents (soap, shower or bath foam, shampoo) which are normally opened with wet hands, thus reducing grip. Moreover, tear-open sachets of the above type are unhygienic, on account of the product, once the sachet is torn open, invariably coming into contact with the outer surface of the sachet close to the tear line (this obviously only applies to food products).
To eliminate the above drawbacks, a break-open as opposed to tear-open package has been proposed. One example of a sealed single-dose break-open package is illustrated in U.S. Pat. No. 6,041,930B1, which describes a package formed from a sheet of semirigid plastic material and a sheet of flexible plastic material superimposed and sealed to each other to define a sealed pocket containing a dose of the product; and the sheet of semirigid plastic material has a straight central incision for guiding controlled breakage of the sheet of semirigid plastic material. In actual use, to open the package, the user simply grips the package with the fingers of one hand, and bends the package to break the sheet of semirigid plastic material along the incision. By so doing, the product flows smoothly and hygienically out of the package, by not coming into contact with the outer surface of the package.
In a sealed single-dose break-open package of the type described in U.S. Pat. No. 6,041,930B1, however, the product flows out extremely fast, with no possibility of regulating flow, particularly in the case of a liquid (i.e. low-density) product. This drawback is substantially due to the sheet of semirigid plastic material being broken instantaneously along practically the whole incision, thus forming a very large outlet.
By way of a solution to the problem, i.e. to permit more controllable outflow of the product, a V-shaped incision has been proposed, as described in U.S. Pat. No. 6,945,391B2. In this case, breakage of the sheet of semirigid plastic material should be limited initially to the central part of the incision (i.e. the tip of the “V”) and then extend along the rest of the incision, so that the user should be able to form a break, and hence a small outlet, limited to the central part of the incision. Various tests, however, show the solution proposed in U.S. Pat. No. 6,945,391B2 also fails to effectively solve the problem of controlling outflow of the product easily and intuitively, particularly in the case of a liquid product.
To produce a sealed single-dose break-open package, U.S. Pat. No. 6,041,930B1 proposes a packing machine, in which a strip of semirigid plastic material and a strip of flexible plastic material are unwound off respective reels and superimposed at a first longitudinal sealing station, where a metering device feeds the product between the two strips, which are then immediately sealed laterally and longitudinally (i.e. parallel to the strips) to form a tube containing the product. Downstream from the longitudinal sealing station, a further transverse sealing station seals the strips transversely (i.e. perpendicular to the strips) to form along a tube a number of pockets, each containing a dose of product. And finally, downstream from the transverse sealing station, a cutting station cuts the two strips transversely to separate the sealed single-dose packages successively.
The sealed single-dose packages produced on the packing machine described above, however, are of poor quality, by having weak transverse seals and containing a large amount of air. It is important to note that a large amount of air inside a sealed single-dose package seriously affects the appearance of the package and, in the case of a food product, greatly reduces the shelf lie of the product.